Effects of Nd:YAG laser irradiation on microcirculation

Changes in microcirculation after irradiation by Nd:YAG laser were evaluated using the "rabbit ear chamber" method. Morphological changes of the vascular network related to time elapsed after irradiation was observed by a microscope-video system. Findings such as vascular shrinkage, degeneration, coagulation, and stasis associated with irradiation were recognized shortly after the Nd:YAG laser was applied. Damage increased with irradiation energy increase. Expansion of the stasis region and appearance of hemorrhagic spots decreased, and vascularization began. On the seventh to tenth days, the damaged region was restored by a newly formed capillary network. When no change was noticed microscopically in the case of low-energy irradiation, transient increase of blood flow, determined by laser Doppler flowmeter, was observed. The results suggest that the effects of Nd:YAG laser irradiation are primarily thermal. It has good hemostatic and coagulation ability and some of the changes are nerve-mediated by low-energy irradiation.